Window and display device including the same

ABSTRACT

A window includes a first folding portion foldable about a first folding axis extended in a first direction, and including upper and lower surfaces facing each other, and a second folding portion foldable about a second folding axis extended in a second direction crossing the first direction, including the upper and lower surfaces, and including a portion of the first folding portion. First upper grooves extended in the first direction and recessed from the upper surface and first lower grooves extended in the first direction and recessed from the lower surface are defined in the first folding portion, and second upper grooves extended in the second direction and recessed from the upper surface and second lower grooves extended in the second direction and recessed from the lower surface are defined in the second folding portion. The portion is defined as a crossing portion in which the grooves are defined.

This application claims priority to Korean Patent Application No.10-2021-0182175, filed on Dec. 17, 2021, and all the benefits accruingtherefrom under 35 U.S.C. § 119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND 1. Field

Embodiments of the invention herein relate to a window and a displaydevice including the same, and more particularly, to a foldable windowand a display device including the same.

2. Description of the Related Art

A display device is used in various multimedia devices such as atelevision, a mobile phone, a tablet computer, a game console, or thelike, to provide image information to a user. Recently, various types offlexible display devices which are foldable or bendable are beingdeveloped. A flexible device may be variously changed in shape, such asbeing folded, rolled, or bent, and thus, has a feature of being easy tocarry.

A flexible display device may include a display panel and a window whichare foldable or bendable. However, there is a problem in that a windowof a flexible display device is deformed by a folding or bendingoperation or is easily damaged by an external impact.

SUMMARY

Embodiments of the invention provide a window having excellent foldingproperties and mechanical physical properties.

Embodiments of the invention also provide a display device including awindow having excellent folding properties and mechanical physicalproperties.

An embodiment of the invention provides a window including a firstfolding portion foldable about a first folding axis extended in a firstdirection, and including an upper surface and a lower surface facingeach other, and a second folding portion foldable about a second foldingaxis extended in a second direction crossing the first direction,including the upper surface, the lower surface, and a portion of thefirst folding portion. A plurality of first upper grooves each of whichis extended in the first direction and recessed from the upper surfaceand a plurality of first lower grooves each of which is extended in thefirst direction and recessed from the lower surface are defined in thefirst folding portion, and a plurality of second upper grooves each ofwhich is extended in the second direction and recessed from the uppersurface and a plurality of second lower grooves each of which isextended in the second direction and recessed from the lower surface aredefined in the second folding portion, wherein the portion of the firstfolding portion included in the second folding portion is defined as acrossing portion. The plurality of first upper grooves, the plurality offirst lower grooves, the plurality of second upper grooves, and theplurality of second lower grooves are disposed in the crossing portion.

In an embodiment, the window may further include a first peripheralportion and a second peripheral portion spaced apart from each other inthe second direction with the first folding portion interposedtherebetween. The plurality of second upper grooves and the plurality ofsecond lower grooves may be defined in a portion of each of the firstperipheral portion and the second peripheral portion.

In an embodiment, each of the first peripheral portion, the firstfolding portion, and the second peripheral portion may be foldable aboutthe second folding axis.

In an embodiment, the window may further include a third peripheralportion and a fourth peripheral portion spaced apart from each other inthe first direction with the second folding portion interposedtherebetween. The plurality of first upper grooves and the plurality offirst lower grooves may be defined in a portion of each of the thirdperipheral portion and the fourth peripheral portion.

In an embodiment, each of the third peripheral portion, the secondfolding portion, and the fourth peripheral portion may be foldable aboutthe first folding axis.

In an embodiment, the plurality of first upper grooves and the pluralityof first lower grooves may not overlap each other in a plan view.

In an embodiment, the plurality of first upper grooves and the pluralityof first lower grooves may be alternately defined with each other.

In an embodiment, the plurality of first upper grooves and the pluralityof first lower grooves may overlap each other in a plan view.

In an embodiment, an average value of heights at which the plurality offirst upper grooves is recessed from the upper surface may besubstantially identical to an average value of heights at which theplurality of first lower grooves is recessed from the lower surface.

In an embodiment, an average value of heights at which the plurality offirst upper grooves is recessed from the upper surface may be differentfrom an average value of heights at which the plurality of first lowergrooves is recessed from the lower surface.

In an embodiment, an average value of widths of the plurality of firstupper grooves measured in the second direction from the upper surfacemay be substantially identical to an average value of widths of theplurality of first lower grooves measured in the second direction fromthe lower surface.

In an embodiment, an average value of widths of the plurality of firstupper grooves measured in the second direction from the upper surfacemay be different from an average value of widths of the plurality offirst lower grooves measured in the second direction from the lowersurface.

In an embodiment, the crossing portion may be defined in a centerportion of each of the first folding portion and the second foldingportion.

In an embodiment, the plurality of first upper grooves each and theplurality of first lower grooves each may be spaced apart from eachother in the second direction, and the plurality of second upper grooveseach and the plurality of second lower grooves each may be spaced apartfrom each other in the first direction.

In an embodiment, the plurality of first upper grooves and the pluralityof first lower grooves may each be symmetrical about the first foldingaxis.

In an embodiment, the plurality of second upper grooves and theplurality of second lower grooves may each be symmetrical around thesecond folding axis.

In an embodiment of the invention, a window includes a first portion, asecond portion, and a third portion sequentially defined in a firstdirection, a fourth portion, a fifth portion, and a sixth portionsequentially defined in the first direction, overlapping each of thefirst to third portions in a second direction crossing the firstdirection, and disposed respectively below the first to third portionsin the second direction, and a seventh portion, an eighth portion, and aninth portion sequentially defined in the first direction, overlappingeach of the first to third portions in the second direction, anddisposed respectively below the fourth to sixth portions in the seconddirection in the second direction. Upper surfaces of the first to ninthportions are disposed in a same plane, and together define a firstsurface, each of lower surfaces of the first to ninth portions aredisposed in a same plane, and together define a second surface, aplurality of first upper grooves recessed from the first surface andextended in the first direction is defined in each of the fourth tosixth portions, and a plurality of second upper grooves recessed fromthe first surface and extended in the second direction is defined ineach of the second portion, the fifth portion, and the eighth portion.

In an embodiment, a plurality of first lower grooves recessed from thesecond surface and extended in the first direction may be furtherdefined in each of the fourth to sixth portions, and a plurality ofsecond lower grooves recessed from the second surface and extended inthe second direction may be further defined in each of the secondportion, the fifth portion, and the eighth portion.

In an embodiment, the fourth to sixth portions may be foldable about afirst folding axis extended in the first direction, and the secondportion, the fifth portion, and the eighth portion may be foldable abouta second folding axis extended in the second direction.

In an embodiment of the invention, a display device includes a foldabledisplay module, and a window disposed on the display module. The windowincludes a first folding portion foldable about a first folding axisextended in a first direction, and including an upper surface and alower surface facing each other, and a second folding portion foldableabout a second folding axis extended in a second direction crossing thefirst direction, including the upper surface and the lower surface, andincluding a portion of the first folding portion. A plurality of firstupper grooves each of which is extended in the first direction andrecessed from the upper surface and a plurality of first lower grooveseach of which is extended in the first direction and recessed from thelower surface are defined in the first folding portion, and a pluralityof second upper grooves each of which is extended in the seconddirection and recessed from the upper surface and a plurality of secondlower grooves each of which is extended in the second direction andrecessed from the lower surface are defined in the second foldingportion. The portion of the first folding portion included in the secondfolding portion is defined as a crossing portion. The plurality of firstupper grooves, the plurality of first lower grooves, the plurality ofsecond upper grooves, and the plurality of second lower grooves aredisposed in the crossing portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explainprinciples of the invention. In the drawings:

FIG. 1 is a perspective view illustrating an embodiment of the state inwhich an electronic device is not folded according to the invention;

FIG. 2A to FIG. 2D are each a perspective view illustrating anembodiment of the state in which an electronic device is foldedaccording to the invention;

FIG. 3A is an exploded perspective view of an embodiment of anelectronic device according to the invention;

FIG. 3B and FIG. 3C are cross-sectional views illustrating an embodimentof the state in which an electronic device is folded according to theinvention;

FIG. 4 is a cross-sectional view of an embodiment of a window moduleaccording to the invention;

FIG. 5A is a perspective view of an embodiment of a window according tothe invention;

FIG. 5B is a plan view of an enlarged portion of an embodiment of awindow according to the invention;

FIG. 5C to FIG. 5E are cross-sectional views illustrating a portion of across-section of a window according to the invention;

FIG. 6A and FIG. 6B are cross-sectional views illustrating an embodimentof a portion of a cross-section of a window according to the invention;

FIG. 7A to FIG. 7C are each a cross-sectional view illustrating anembodiment of a portion of a cross-section of a window according to theinvention;

FIG. 8A and FIG. 8B are cross-sectional views illustrating an embodimentof a portion of a cross-section of a window according to the invention;

FIG. 9A to FIG. 9E are cross-sectional views illustrating an embodimentof a portion of a cross-section of a window according to the invention;

FIG. 10 is a cross-sectional view illustrating an embodiment of aportion of a cross-section of a window according to the invention;

FIG. 11 is a cross-sectional view illustrating an embodiment of aportion of a cross-section of a window according to the invention;

FIG. 12 is a flowchart of an embodiment of a method for manufacturing awindow according to the invention; and

FIG. 13A to FIG. 13C are views illustrating an embodiment of eachoperation of a method for manufacturing a window according to theinvention.

DETAILED DESCRIPTION

In the disclosure, when an element (or a region, a layer, a portion,etc.) is referred to as being “on,” “connected to,” or “coupled to”another element, it means that the element may be directly disposedon/connected to/coupled to the other element, or that a third elementmay be disposed therebetween.

Like reference numerals refer to like elements. Also, in the drawings,the thickness, the ratio, and the dimensions of elements are exaggeratedfor an effective description of technical contents. The term “and/or”includes any and all combinations of one or more of which associatedelements may define.

It will be understood that, although the terms “first,” “second,” etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another. For example, a first element may be referredto as a second element, and a second element may also be referred to asa first element in a similar manner without departing the scope ofrights of the invention. The terms of a singular form may include pluralforms unless the context clearly indicates otherwise.

In addition, terms such as “below,” “lower,” “above,” “upper,” and thelike are used to describe the relationship of the elements shown in thedrawings. The terms are used as a relative concept and are describedwith reference to the direction indicated in the drawings.

It should be understood that the terms “comprise,” or “have” areintended to specify the presence of stated features, integers, steps,operations, elements, components, or combinations thereof in thedisclosure, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components, orcombinations thereof

In the disclosure, being “directly disposed” may mean that there is nolayer, film, region, plate, or the like added between a portion of alayer, a film, a region, a plate, or the like and other portions. Forexample, being “directly disposed” may mean being disposed withoutadditional members such as an adhesive member between two layers or twomembers.

“About” or “approximately” as used herein is inclusive of the statedvalue and means within an acceptable range of deviation for theparticular value as determined by one of ordinary skill in the art,considering the measurement in question and the error associated withmeasurement of the particular quantity (i.e., the limitations of themeasurement system). The term “about” can mean within one or morestandard deviations, or within ±30%, 20%, 10%, 5% of the stated value,for example.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the invention pertains. It is alsoto be understood that terms such as terms defined in commonly useddictionaries should be interpreted as having meanings consistent withthe meanings in the context of the related art, and should not beinterpreted in too ideal a sense or an overly formal sense unlessexplicitly defined herein.

Hereinafter, embodiments of the invention will be described withreference to the accompanying drawings.

FIG. 1 is a perspective view illustrating an embodiment of the state inwhich an electronic device is not folded according to the invention.FIG. 2A to FIG. 2D are each a perspective view illustrating anembodiment of the state in which an electronic device is foldedaccording to the invention.

An electronic device ED may be a device activated in accordance with anelectrical signal to provide an image IM. In FIG. 1 , the electronicdevice ED is illustrated as a smart phone as an example. However, theinvention is not limited thereto, and the electronic device ED of theinvention may be a large-sized electronic device such as a televisionand a monitor, and may be a small-and-medium-sized electronic devicesuch as a mobile phone, a tablet computer, a car navigation system unit,and a game console. In addition, without departing from the inventiveconcept, the electronic device ED may be used in a variety of electronicdevices without being limited to the examples described above.

Referring to FIG. 1 , the front surface of the electronic device ED maybe defined as a display surface IS. When not folded, the display surfaceIS of the electronic device ED may correspond to a surface defined by afirst direction DR1 and a second direction DR2 crossing the firstdirection DR1. The display surface IS may display the image IM toward athird direction DR3.

In the drawings of the invention, the first to third directions DR1,DR2, and DR3 are illustrated, and the first to third directions DR1,DR2, and DR3 described in the disclosure are relative concepts, and maybe converted to different directions. Directions indicated by the firstto third directions DR1, DR2, and DR3 are illustrated using the samereference numerals in each of the drawings.

In the disclosure, the front surface (or upper surface) and the rearsurface (or lower surface) of each component may be defined with respectto a direction in which the image IM is displayed. The upper surface andthe lower surface face each other in the third direction DR3, and thenormal direction of each of the upper surface and the lower surface maybe parallel to the third direction DR3. A distance spaced apart alongthe third direction DR3 between the upper and lower surfaces of acomponent may correspond to the thickness of the component. A term “in aplan view” in the disclosure may correspond to viewing a component inthe third direction DR3.

The display surface IS of the electronic device ED may include a displayregion DA and a non-display region NDA. The display region DA may be aregion in which the image IM is displayed. The non-display region NDAmay be a region in which the image IM is not displayed. A user mayvisually recognize the image IM displayed through the display region DA.The image IM may a moving image or a still image. In an embodiment ofthe image IM, a plurality of application icons, a clock widget, or thelike are illustrated in FIG. 1 .

The display region DA may have a quadrangular shape. However, this isonly exemplary, and the shape of the display region DA may be variouslydesigned. The non-display region NDA may surround the display region DA.However, the invention is not limited thereto, and the non-displayregion NDA may be adjacent to only one side of the display region DA, ormay be omitted.

As illustrated in FIG. 1 , the electronic device ED may have aquadrangular (e.g., rectangular) shape which includes short sidesextended along the first direction DR1, long sides extended along thesecond direction DR2, and rounded corners. However, the shape of theelectronic device ED is not limited thereto, and the electronic deviceED may be provided in various shapes.

Although the electronic device ED in which a one-sided display surfaceIS is illustrated, the electronic device ED may have a double-sideddisplay surface in which the display surface IS is defined on both ofthe front surface and the rear surface. A display surface of theelectronic device ED is not limited to any particular embodiment.

The electronic device ED in an embodiment may be a foldable electronicdevice. The electronic device ED may be foldable about a virtual foldingaxis extended in a predetermined direction. FIG. 1 illustrates a firstfolding axis FX1 extended along the first direction DR1, and a secondfolding axis FX2 extended along the second direction DR2. The firstfolding axis FX1 may be parallel to a short-side direction of theelectronic device ED. The second direction FX2 may be parallel to along-side direction of the electronic device ED. The electronic deviceED in an embodiment may be folded about each of the first folding axisFX1 and the second folding axis FX2. In an embodiment, the electronicdevice ED may be folded about the first folding axis FX1, and/or may befolded about the second folding axis FX2, for example.

FIG. 2A and FIG. 2B illustrate perspective views in which an embodimentof the electronic device ED is folded about the first folding axis FX1.FIG. 2C and FIG. 2D illustrate perspective views in which an embodimentof the electronic device ED is folded about the second folding axis FX2.

The perspective views illustrated in FIG. 2A to FIG. 2D may beperspective views of one electronic device ED. Specifically, theelectronic device ED illustrated in FIG. 2C and FIG. 2 may be theelectronic device ED illustrated in FIG. 2A and FIG. 2B folded about thesecond folding axis FX2.

The electronic device ED may be divided into a folding region and anon-folding region depending on the type of an operation. The foldingregion may be a region bent to have a predetermined curvature when theelectronic device ED is folded about a folding axis. The non-foldingregion may be a flat region when the electronic device ED is foldedabout a folding axis.

The electronic device ED may include at least one folding region and atleast one non-folding region. The definition of the folding region andthe non-folding region may be defined relative to a folding axis. In anembodiment, each of a folding region and a non-folding region definedwhen the electronic device ED is folded about the first folding axis FX1may not be the same as a folding region and a non-folding region definedwhen the electronic device ED is folded about the second folding axisFX2, for example.

Referring to FIG. 2A and FIG. 2B, the electronic device ED folded aboutthe first folding axis FX1 may include a first folding region FA1, afirst non-folding region NFA1, and a second non-folding region NFA2. Thefirst folding region FA1 may be a region folded at a predeterminedcurvature while surrounding the first folding axis FX1. The firstnon-folding region NFA1 may be adjacent to one side of the first foldingregion FA1 along the second direction DR2, and the second non-foldingregion NFA2 may be adjacent to the other side of the first foldingregion FA1 along the second direction DR2.

Referring to FIG. 2C and FIG. 2D, the electronic device ED folded aboutthe second folding axis FX2 may include a second folding region FA2, athird non-folding region NFA3, and a fourth non-folding region NFA4. Thesecond folding region FA2 may be a region folded at a predeterminedcurvature while surrounding the second folding axis FX2. The thirdnon-folding region NFA3 may be adjacent to one side of the secondfolding region FA2 along the first direction DR1, and the fourthnon-folding region NFA4 may be adjacent to the other side of the secondfolding region FA2 along the first direction DR1.

Each of the FIG. 2A to FIG. 2D illustrates one folding axis, but thenumber of folding axes is not limited thereto, and the number of foldingregions and non-folding regions is not also limited to what isillustrated.

The electronic device ED may be in-folded or out-folded. When thedisplay surface IS overlapping a folding region of the electronic deviceED is folded to face a folding axis, it may be defined as in-folding.When a rear surface overlapping a folding region of the electronicdevice ED is folded to face a folding axis, it may be defined asout-folding. The electronic device ED may be manufactured to be capableof both in-folding and out-folding operations, or may be manufactured tobe capable of any one of in-folding and out-folding operations.

FIG. 2A illustrates the electronic device ED in-folded about the firstfolding axis FX1, and FIG. 2C illustrates the electronic device EDin-folded about the second folding axis FX2. FIG. 2B illustrates theelectronic device ED out-folded about the first folding axis FX1, andFIG. 2D illustrates the electronic device ED out-folded about the secondfolding axis FX2.

Referring to FIG. 2A, portions of the display surface IS respectivelyoverlapping the first non-folding region NFA1 and the second non-foldingregion NFA2 of the in-folded electronic device ED may face each other.Referring to FIG. 2C, portions of the display surface IS respectivelyoverlapping the third non-folding region NFA3 and the fourth non-foldingregion NFA4 of the in-folded electronic device ED may face each other.The rear surface of the in-folded electronic device ED may be exposed tothe outside.

Referring to FIG. 2B, the display surface IS overlapping the firstnon-folding region NFA1 and the second non-folding region NFA2 of theout-folded electronic device ED may be exposed to the outside indirections opposite to each other. Referring to FIG. 2D, the displaysurface IS overlapping the third non-folding region NFA3 and the fourthnon-folding region NFA4 of the out-folded electronic device ED may beexposed to the outside in directions opposite to each other. Through theabove, the image IM provided by the electronic device ED in a foldedstate may be visually recognized by a user.

FIG. 3A is an exploded perspective view of an embodiment of anelectronic device according to the invention. FIG. 3B and FIG. 3C arecross-sectional views illustrating an embodiment of the state in whichan electronic device is folded according to the invention.

Referring FIG. 3A to FIG. 3C, the electronic device ED may include adisplay device DD and a housing EDC which receives the display deviceDD.

The display device DD may include a display module DM, a window moduleWM, and adhesive layer AD.

The display module DM may display an image in accordance with anelectrical signal, and may transmit and receive information on anexternal input. The display module DM may include an active region AAand a peripheral region NAA.

The active region AA may be defined as a region activated in accordancewith an electrical signal. In an embodiment, the display module DM mayemit an image through the active region AA, or may sense various typesof external inputs, for example. The active region AA may correspond toat least a portion of the display region DA.

The peripheral region NAA may be adjacent to the active region AA. In anembodiment, the peripheral region NAA may surround the active region AA,for example. However, this is only exemplary, and the peripheral regionNAA may be adjacent to one side of the active region AA, or may beomitted. The peripheral region NAA may correspond to at least a portionof the non-display region NDA.

Although not separately illustrated, the display module DM may include adisplay panel. The display panel may generate an image emitted from thedisplay module DM. The display panel may be a light-emitting-typedisplay panel, but is not particularly limited thereto. In anembodiment, the display panel may be an organic light-emitting displaypanel or a quantum dot light-emitting display panel, for example. Thedisplay module DM may further include an input sensor disposed on thedisplay panel and sense external inputs.

The display module DM may include a plurality of pixels disposed in theactive region AA and a circuit unit disposed on the peripheral regionNAA. The circuit unit may provide an electrical signal to the pixels todrive the pixels. The pixels may be arranged while forminglight-emitting patterns in the active region AA. A light-emittingpattern of a pixel to which an electrical signal is applied from thecircuit unit may emit light in correspondence to the electrical signal,through which an image may be output in the active region AA.

The window module WM may be disposed on the display module DM. Thewindow module WM may cover the entire upper surface of the displaymodule DM. The shape of the window module WM may correspond to the shapeof the display module DM. The window module WM may mitigate an externalimpact, thereby preventing the display module DM from being damaged ormalfunctioning due to the external impact.

The window module WM may include an optically transparent material. Thewindow module WM may include an optically transparent substrate to bedescribed later. In an embodiment, the window module WM may include aglass substrate, and the glass substrate may be a chemically reinforcedtempered glass substrate, for example.

The window module WM may have a single-layered structure or amulti-layered structure. In an embodiment, the window module WM may havea single-layered structure including a glass substrate, but is notlimited to, and may have a multi-layered structure including a coatingfilm coated on a glass substrate, a filling member, or a polymer filmdisposed on the glass substrate, for example.

The front surface of the window module WM may correspond to the frontsurface of the display device DD. In addition, the front surface of thewindow module WM may correspond to the display surface IS of theelectronic device ED described above. The window module WM may includethe display region DA and the non-display region NDA described above.

The display region DA of the window module WM may transmit an imageemitted by the display module DM. A user may visually recognize an imagethrough the display region DA of the window module WM. The window moduleWM may have a predetermined color by overlapping the non-display regionNDA. In an embodiment, the window module WM may further include a printlayer formed or disposed on a glass substrate by overlapping thenon-display region NDA, for example.

The window module WM may be flexible. The window module WM may be foldedtogether with the display module DM about the first folding axis FX1 orthe second folding axis FX2.

The window module WM in an embodiment may include a first folding regionFA1 bent to have a predetermined curvature when folded about the firstfolding axis FX1, and a plurality of non-folding regions NFA1 and NFA2adjacent to the first folding region FA1. The window module WM in anembodiment may include a second folding region FA2 bent to have apredetermined curvature when folded about the second folding axis FX2,and a plurality of non-folding regions NFA3 and NFA4 adjacent to thesecond folding region FA2.

In FIG. 3 , the window module WM is illustrated in a quadrangular shapeincluding rounded corners. However, this is only illustrative, and thewindow module WM may have various shapes in correspondence to thedisplay module DM. The shape of the window module WM may vary dependingon the design of a substrate manufactured through a manufacturingprocess of the window module WM.

The adhesive layer AD may be disposed between the window module WM andthe display module DM. The adhesive layer AD may adhere the windowmodule WM and the display module DM. In an embodiment, the adhesivelayer AD may be an optically clear adhesive film (“OCA”), an opticallyclear adhesive resin layer (“OCR”), or a pressure sensitive adhesive(“PSA”). The adhesive layer AD may be formed or provided as one bodywith a filling member of the window module WM to be described later, butis not limited to any particular embodiment. In an embodiment, theadhesive layer AD may be omitted.

Although not separated illustrated, the display device DD may furtherinclude at least one functional layer disposed between the displaymodule DM and the window module WM. In an embodiment, the display deviceDD may further include a refection prevention layer which reduces thereflectance of external light incident from above the window module WM,for example. In addition, the display device DD may further include atleast one of a protective layer, a cushion layer, or a support moduledisposed below the display module DM.

The electronic device ED may include a housing EDC which receives thedisplay device DD. The housing EDC may be coupled to the window moduleWM.

The housing EDC may include a first hinge HN1 folded or bent based onthe first folding axis FX1, a second hinge HN2 folded or bent based onthe second folding axis FX2, and a plurality of cases ST1, ST2, ST3, andST4. The plurality of cases ST1, ST2, ST3, and ST4 may be coupled toeach other through the first hinge HN1 and the second hinge HN2.

During folding and unfolding operations of the electronic device ED, theelectronic device ED may perform the folding and unfolding operationsbased on each of the first hinge HN1 and the second hinge HN2.

The plurality of cases ST1, ST2, ST3, and ST4 may include a first caseST1 simultaneously overlapping a first non-folding region NFA1 and athird non-folding region NFA3, a second case ST2 simultaneouslyoverlapping a second non-folding region NFA2 and the third non-foldingregion NFA3, a third case ST3 simultaneously overlapping the secondnon-folding region NFA2 and a fourth non-folding region NFA4, and afourth case ST4 simultaneously overlapping the first non-folding regionNFA1 and the fourth non-folding region NFA4.

Referring to FIG. 3B, the electronic device ED in an embodiment may befolded based on the first folding axis FX1 by the first hinge HN1. Atthis time, the first case ST1 and the second case ST2 may face eachother. In an embodiment, the first case ST1 and the second case ST2 areillustrated as being spaced apart from each other, but the invention isnot limited thereto, and at least a portion of the first case ST1 maycontact the second case ST2. Although not illustrated, as the firsthinge HN1 is folded, the third case ST3 and the fourth case ST4 may faceeach other.

Referring to FIG. 3C, the electronic device ED in an embodiment may befolded based on the second folding axis FX2 by the second hinge HN2. Atthis time, the second case ST2 and the third case ST3 may face eachother. In an embodiment, the second case ST2 and the third case ST3 areillustrated as being spaced apart from each other, but the invention isnot limited thereto, and at least a portion of the second case ST2 maycontact the third case ST3. Although not illustrated, as the secondhinge HN2 is folded, the first case ST1 may face the fourth case ST4.

The electronic device ED includes the first hinge HN1 and the secondhinge NH2, and thus, may be folded based on each of the first foldingaxis FX1 and the second folding axis FX2.

FIG. 4 is a cross-sectional view of an embodiment of a window moduleaccording to the invention. FIG. 4 is a cross-sectional view of anembodiment in which the window module WM is cut in one direction.

Referring to FIG. 4 , the window module WM may include a window PG and awindow protection layer PL. The window module WM in an embodiment mayfurther include a first filling layer FL1 disposed on an upper portionof the window PF and a second filling layer FL2 disposed on a lowerportion of the window PG.

The window PG may include an optically transparent material. In anembodiment, the window PG may include a glass substrate, and the glasssubstrate may be a chemically reinforced tempered glass substrate, forexample. By including a glass substrate, the window PG may haveexcellent aesthetics, and may be prevented from being imprinted orscratched by a sharp material.

The window PG may include an upper surface PG-F and a lower surface PG-Bopposite to each other. In an embodiment, the upper surface PG-F and thelower surface PG-B may face each other in the third direction DR3. Thewindow PG may have a predetermined thickness along the third directionDR3. The thickness of the window PG may affect the impact resistance ofthe window PG. When the window PG is too thin, the window PG may bebroken or damaged by an impact focused on a local region (e.g., animpact by a pen drop). When the window PG is too thick, the flexibilitythereof may be degraded or the window PG may be broken when folded. Inan embodiment, the thickness of the window PG may be about 100micrometers (μm), for example. In an embodiment, the thickness of thewindow PG may be about 100 μm to about 1000 μm. In an embodiment, thethickness of the window PG may be about 300 μm to about 700 μm. However,the thickness of the window PG is not necessarily limited to the abovenumerical value examples. When the thickness of the window PG satisfiesthe above range, the impact resistance of the window PG is ensured, sothat the display module DM to be disposed below the window PG may beprotected from external impacts.

The window PG may include a folding portion FP and a peripheral portionNFP defined in one direction. The folding portion FP may be a portionfolded about any one of the first folding axis FX1 and the secondfolding axis FX2 described above in one direction.

The peripheral portion NFP may be a portion adjacent to the foldingportion FP. The peripheral portion NFP may be a portion not folded inthe one direction.

An upper groove having a recessed shape in the upper surface PG-F and alower groove GB having a recessed shape in the lower surface PG-B may bedefined in the folding portion FP.

FIG. 4 illustrates six upper grooves GU and six lower grooves GBrecessed along the third direction DR3 in the folding portion FP.However, the number of each of the upper groove GU and the lower grooveGB is not limited to what is illustrated, and one or more, five or less,or seven or more of each of the upper groove GU and the lower groove GBmay be defined.

The peripheral portion NFP may be a portion adjacent to the foldingportion FP. The upper groove GU and the lower groove GB may not bedefined in the peripheral portion NFP.

The upper groove GU and the lower groove GB are defined in the foldingportion FP, and thus, may have improved folding properties compared tothe peripheral portion NFP. Specifically, the upper groove GU and thelower groove GB are defined in the folding portion FP, and thus, thefolding portion FP may be relatively thinner than the peripheral portionNFP, and may have improved flexibility. Accordingly, the stress appliedto the window PG when the electronic device ED is folded may be reduced,and the damage caused by the folding of the window PG may be prevented.

However, the definition of the folding portion FP and the peripheralportion NFP may be relative to a folding direction. The window PG of theinvention may be folded about each of the first folding axis FX1 and thesecond folding axis FX2. A folding portion FP and a peripheral portionNFP defined when the window PG is folded about the first folding axisFX1 may be different from a folding portion FP and a peripheral portionNFP defined when the window PG is folded about the second folding axisFX2.

When the window module WM is cut in a different direction from thecutting direction of the window module WM illustrated in FIG. 4 , theupper groove GU and the lower groove GB may also be defined in theperipheral portion NFP of the window PG illustrated in FIG. 4 , and aportion of the peripheral portion NFP may be folded in the differentdirection. The folding portion FP and the peripheral portion NFP will bedescribed in detail later.

The first and second filling layers FL1 and FL2 may be respectivelydisposed in the upper portion and the lower portion of the window PG.The first and second filling layers FL1 and FL2 may respectively overlapthe folding portion FP and the peripheral portion NFP of the window PG.In an embodiment, the upper groove GU and the lower groove GB may befilled by the first and second filling layers FL1 and FL2. In analternative embodiment, optionally, the first and second filling layersFL1 and FL2 may be provided only to the folding portion FP to fill theupper groove GU and the lower groove GB.

An upper surface of the first filling layer FL1 may be a flat surface,and a lower surface of the second filling layer FL2 may be a flatsurface.

The first and second filling layers FL1 and FL2 may include a syntheticresin material. The first and second filling layers FL1 and FL2 of anexample may include a material having the same refractive index as thatof the window PG. In an embodiment, the first and second filling layersFL1 and FL2 may include at least one of a urethane-based resin, anepoxy-based resin, a polyester-based resin, a polyether-based resin, anacrylate-based resin, an acrylonitrile-butadiene-styrene(“ABS”) resin,or rubber, for example. Specifically, each of the filling layers FL1 andFL2 may include at least one of phenylene, polyethyleneterephthalate(“PET”), polyimide (“PI”), polyamide (“PAI”), polyethylene naphthalate(“PEN”), or polycarbonate (“PC”).

The window protection layer PL may be disposed on the window PG. Thewindow protection layer PL may be provided on the first filling layerFL1. The window protection layer PL may perform a function of protectingthe window PG from external impacts.

The window protection layer PL may include a synthetic resin material.In an embodiment of the invention, the window protection layer PL mayinclude at least one of a urethane-based resin, an epoxy-based resin, apolyester-based resin, a polyether-based resin, an acrylate-based resin,an ABS resin, or rubber. Specifically, the window protection layer PLmay include at least one of phenylene, PET, PI, PAI, PEN, or PC.

The window protection layer PL may have a single-layered structure or amulti-layered structure. In an embodiment, the window protection layerPL may have a single-layered structure including a synthetic resinmaterial, but is not limited thereto, and may have a multi-layeredstructure further including at least one of a hard coating layer, ananti-fingerprint layer, or an anti-fouling layer in addition to a layerincluding a synthetic resin material, for example.

FIG. 5A is a perspective view of an embodiment of a window according tothe invention.

Referring to FIG. 5A, the window PG in an embodiment may have a cuboidshape including the upper surface PG-F and the lower surface PG-Brespectively parallel to the first direction DR1 and the seconddirection DR2, and having a thickness defined along the third directionDR3. FIG. 5A illustrates the window PF having right-angled corners.However, the invention is not limited thereto, and the window PG of FIG.5A may have a cuboid shape with rounded corners.

The window PG of the invention is folded about the first folding axisFX1 extended in the first direction DR1, and is folded about the secondfolding axis FX2 extended in the second direction DR2.

In an embodiment, FIG. 5A illustrates a case in which the first andsecond folding axes FX1 and FX2 are disposed on the upper surface PG-Fof the window PG. When the electronic device ED is folded, the uppersurface PG-F may be folded while surrounding the first folding axis FX1or the second folding axis FX2. However, the embodiment of the inventionis not necessarily limited thereto, and the first and second foldingaxes FX1 and FX2 may be disposed below the lower surface PG-B of thewindow PG. In this case, when the electronic device ED is folded, thelower surface PG-B of the window PG may be folded while surrounding thefirst folding axis FX1 or the second folding axis FX2.

The window PG includes a first portion PT1, a second portion PT2, athird portion PT3, a fourth portion PT4, a fifth portion PT5, a sixthportion PT6, a seventh portion PT7, an eighth portion PT8, and a ninthportion PT9. The first portion PT1, the second portion PT2, and thethird portion PT3 are sequentially defined in the first direction DR1.The fourth portion PT4, the fifth portion PT5, and the sixth portion PT6are sequentially defined in the first direction DR1. The fourth portionPT4, the fifth portion PT5, and the sixth portion PT6 respectivelyoverlap the first portion PT1, the second portion PT2, and the thirdportion PT3 in the second direction DR2.

The seventh portion PT7, the eighth portion PT8, and the ninth portionPT9 are sequentially defined in the first direction DR1. The seventhportion PT7, the eighth portion PT8, and the ninth portion PT9respectively overlap the fourth portion PT4, the fifth portion PT5, andthe sixth portion PT6 in the second direction DR2. The seventh portionPT7, the eighth portion PT8, and the ninth portion PT9 may respectivelyoverlap the first portion PT1, the second portion PT2, and the thirdportion PT3 in the second direction DR2.

In the second direction DR2, the fourth portion PT4, the fifth portionPT5, and the sixth portion PT6 are respectively disposed below the firstportion PT1, the second portion PT2, and the third portion PT3. In thesecond direction DR2, the seventh portion PT7, the eighth portion PT8,and the ninth portion PT9 are respectively disposed below the fourthportion PT4, the fifth portion PT5, and the sixth portion PT6.

The first to ninth portions PT1, PT2, PT3, PT4, PT5, PT6, PT7, PT8, andPT9 may be disposed on the same plane. Specifically, an upper surface ofeach of the first to ninth portions PT1, PT2, PT3, PT4, PT5, PT6, PT7,PT8, and PT9 together may define a surface of a single plane. In anembodiment, the upper surface of each of the first to ninth portionsPT1, PT2, PT3, PT4, PT5, PT6, PT7, PT8, and PT9 together may define afirst surface of a single plane, for example. The first surface maycorrespond to the upper surface PG-F of the window PG.

Specifically, a lower surface of each of the first to ninth portionsPT1, PT2, PT3, PT4, PT5, PT6, PT7, PT8, and PT9 together may define asurface of a single plane. In an embodiment, the lower surface of eachof the first to ninth portions PT1, PT2, PT3, PT4, PT5, PT6, PT7, PT8,and PT9 together may define a second surface of a single plane, forexample. The second surface may correspond to the lower surface PG-B thewindow PG.

The upper groove GU (refer to FIG. 4 ) and the lower groove GB (refer toFIG. 4 ) are defined in the window PG. The upper groove GU (refer toFIG. 4 ) may include a first upper grooves GU1 and a second uppergrooves GU2. The lower groove GB (refer to FIG. 4 ) may include a firstlower grooves GB1 and a second lower grooves GB2.

Each of the first upper grooves GU1 and the second upper grooves GU2 hasa shape recessed in the upper surface PG-F. Each of the first uppergrooves GU1 is extended in the first direction DR1. Each of the secondupper grooves GU2 is extended in the second direction DR2.

The first upper groove GU1 may be spaced apart in the second directionDR2, and the second upper grooves GU2 may be spaced apart in the firstdirection DR1.

Each of the first lower grooves GB1 and the second lower grooves GB2 hasa shape recessed in the lower surface PG-B. Each of the first lowergrooves GB1 is extended in the first direction DR1. Each of the secondlower grooves GB2 is extended in the second direction DR2.

The first lower grooves GB1 may be spaced apart in the second directionDR2, and the second lower grooves GB2 may be spaced apart in the firstdirection DR1.

Specifically, the first upper grooves GU1 and the first lower groovesGB1 are defined in each of the fourth to sixth portions PT4, PT5, andPT6. Accordingly, each of the fourth portion PT4, the fifth portion PT5,and the sixth portion PT6 may be folded about the first folding axis FX1parallel to the first direction DR1. Based on the first folding axisFX1, the fourth portion PT4, the fifth portion PT5, and the sixthportion PT6 may correspond to the folding portion FP described abovewith reference to FIG. 4 . The first portion PT1, the second portionPT2, the third portion PT3, the seventh portion PT7, the eighth portionPT8, and the ninth portion PT9 may correspond to the peripheral portionNFP described above with reference to FIG. 4 .

The second upper grooves GU2 and the second lower grooves GB2 aredefined in each of the second portion PT2, the fifth portion PT5, andthe eighth portion PT8. Accordingly, each of the second portion PT2, thefifth portion PT5, and the eighth portion PT8 may be folded about thesecond folding axis FX2 parallel to the second direction DR2. Based onthe second folding axis FX2, the second portion PT2, the fifth portionPT5, and the eighth portion PT8 may correspond to the folding portion FPdescribed above with reference to FIG. 4 . The first portion PT1, thethird portion PT3, the fourth portion PT4, the sixth portion PT6, theseventh portion PT7, and the ninth portion PT9 may correspond to theperipheral portion NFP described above with reference to FIG. 4 .

The fifth portion PT5 may be folded about the first folding axis FX1,and about the second folding axis FX2.

The first upper grooves GU1, the first lower grooves GB1, the secondupper grooves GU2, and the second lower grooves GB2 are defined in thewindow PG of the invention, and thus, the window PG of the invention mayhave improved folding properties. Specifically, the window PG of theinvention may be folded about the first folding axis FX1 by the firstupper grooves GU1 and the first lower grooves GB1, and may be foldedabout the second folding axis FX2 by the second upper grooves GU2 andthe second lower grooves GB2.

FIG. 5B is a plan view of an embodiment of an enlarged portion of awindow according to the invention.

FIG. 5B is a plan view of an embodiment in which a portion of the fifthportion PT5 of FIG. 5A is enlarged.

Referring to FIG. 5B, the first upper grooves GU1, the first lowergrooves GB1, the second upper grooves GU2, and the second lower groovesGB2 are defined in the fifth portion PT5.

In a plan view, the first upper grooves GU1 and the second upper groovesGU2 may be defined on a front surface of the window PG, and the firstlower grooves GB1 and the second lower grooves GB2 may be defined on arear surface of the window PG. The first lower grooves GB1 and thesecond lower grooves GB2 defined on the rear surface are marked withhatching. In an embodiment, in FIG. 5B, three first upper grooves GU1-a,GU1-b, and GU1-c, two first lower grooves GB1-a and GB1-b, two secondupper grooves GU2-a and GU2-b, and three second lower grooves GB2-a,GB2-b, and GB2-c are illustrated, but the number of each groove is notlimited thereto.

Each of the first upper grooves GU1 and the first lower grooves GB1 isextended in the first direction DR1. Each of the second upper groovesGU2 and the second lower grooves GB2 is extended in the second directionDR1.

In a plan view, the first upper grooves GU1 may cross the second uppergrooves GU2. In an embodiment, the first upper groove GU1-a may crossthe second upper groove GU2-a at a first point Po1, for example.

In the same manner, in a plan view, the first lower grooves GB1 maycross the second lower grooves GB2. In an embodiment, the first lowergroove GB1-a may cross the second upper groove GU2-a at a second pointPo2, for example.

In the window PG of the invention, at the fifth portion PT5, the firstupper grooves GU1 and the second upper grooves GU2 may cross each other,and the first lower grooves GB1 and the second lower grooves GB2 maycross each other. The fifth portion PT5 may be defined as a crossingportion.

FIG. 5C to FIG. 5E are cross-sectional views illustrating an embodimentof a portion of a cross-section of a window according to the invention.

FIG. 5C is a cross-sectional view of taken along line I-I′ illustratedin FIG. 5A. The cutting line I-I′ of FIG. 5A may be parallel to thesecond direction DR2.

Referring to FIG. 5A and FIG. 5C together, the window PG of theinvention may include a first folding portion FP1 folded about the firstfolding axis FX1 and a first peripheral portion NFP1 and a secondperipheral portion NFP2 which are adjacent to the first folding portionFP1. The first peripheral portion NFP1 and the second peripheral portionNFP2 may be spaced apart from each other in the second direction DR2with the first folding portion FP1 interposed therebetween.

The fourth to sixth portions PT4, PT5, and PT6 may correspond to thefirst folding portion FP1. The first to third portions PT1, PT2, and PT3may correspond to the first peripheral portion NFP1. The seventh toninth portions PT7, PT8, and PT9 may correspond to the second peripheralportion NFP2.

Based on the first folding axis FX1, the first folding portion FP1 maybe defined as the first folding region FA1, and the first peripheralportion NFP1 and the second peripheral portion NFP2 may be respectivelydefined as the first and second non-folding regions NFA1 and NFA2.

In the first folding portion FP1, the first upper groove GU1 and thefirst lower groove GB1 may be defined.

In an embodiment, the first upper groove GU1 and the first lower grooveGB1 may not overlap each other in a plan view. In the second directionDR2, the first upper groove GU1 and the first lower groove GB1 may havea shape of being alternately defined.

Each of the first upper grooves GU1 has a shape of being recessed in theupper surface PG-F, and may have, specifically, a shape of beingrecessed in a direction from the upper surface PG-F to the lower surfacePG-B. A height t1 of the first upper grooves GU1 may be defined as anaverage value of maximum values of depths at which each of the firstupper grooves GU1 is recessed in the direction from the upper surfacePG-F to the lower surface PG-B. Here, the maximum values of the depthsmay mean depths measured from the upper surface PG-F to respectivepoints of the first upper grooves GU1 farthest from the upper surfacePG-F in the third direction DR3.

In an embodiment, when the thickness of the window PG is set to t0, theheight t1 of the first upper grooves GU1 may be set to a value of“greater than 0 μm to (t0-100) μm or less.” That is, the minimum valueof thicknesses from the lower surface PG-B of the window PG to the firstupper grooves GU1 may be about 100 μm.

In an embodiment, when the thickness t0 of the window PG is about 300μm, the height t1 of the first upper grooves GU1 may be set to a valueof greater than 0 μm to 200 μm or less, for example. In an embodiment,when the thickness t0 of the window PG is about 700 μm, the height t1 ofthe first upper grooves GU1 may be set to a value of greater than 0 μmto 600 μm or less, for example.

Each of the first lower grooves GB1 has a shape of being recessed in thelower surface PG-B, and may have, specifically, a shape of beingrecessed in a direction from the lower surface PG-B to the upper surfacePG-F. A height t2 of the first lower grooves GB1 may be defined as anaverage value of maximum values of depths at which each of the firstlower grooves GB1 is recessed in the direction from the lower surfacePG-B to the upper surface PG-F.

In an embodiment, when the thickness of the window PG is set to t0, theheight t2 of the first lower grooves GB1 may be set to a value of“greater than 0 μm to (t0-100) μm or less.” That is, the minimum valueof thicknesses from the upper surface PG-F of the window PG to the firstlower grooves GB1 may be about 100 μm.

In an embodiment, when the thickness t0 of the window PG is about 300μm, the height t2 of the first lower grooves GB1 may be set to a valueof greater than 0 μm to 200 μm or less, for example. In an embodiment,when the thickness t0 of the window PG is about 700 μm, the height t2 ofthe first lower grooves GB1 may be set to a value of greater than 0 μmto 600 μm or less, for example.

However, the height t1 of the first upper grooves GU1 and the height t2of the first lower grooves GB1 are not necessarily limited to the abovenumerical value examples.

In an embodiment as illustrated in FIG. 5B, the height t1 of the firstupper grooves GU1 may substantially be the same as the height t2 of thefirst lower grooves GB1. However, the invention is not limited thereto.

A portion of the window PG overlapping the first upper grooves GU1 andthe first lower grooves GB1 is relatively thin, so that the foldingproperties of the window PG may be improved, and a portion of the windowPG not overlapping the first upper grooves GU1 and the first lowergrooves GB1 is relatively thick, so that the impact resistance of thewindow PG may be improved.

A width P1 of the first upper grooves GU1 may be defined as an averagevalue of the widths of the first upper grooves GU1 measured in thesecond direction DR2 on the upper surface PG-F. In an embodiment, eachof the widths of the first upper grooves GU1 may gradually decrease asfarther from the upper surface PG-F, and therefore the widths of thefirst upper grooves GU1 measured in the second direction DR2 on theupper surface PG-may be maximum values, but the invention is not limitedthereto.

A width P2 of the first lower grooves GB1 may be defined as an averagevalue of the widths of the first lower grooves GB1 measured in thesecond direction DR2 on the lower surface PG-B.

The width P1 of the first upper grooves GU1 and the width P2 of thefirst lower grooves GB1 may each be set to a value of about 80 μm toabout 200 μm. In an embodiment, the width P1 of the first upper groovesGU1 and the width P2 of the first lower grooves GB1 may each be set to avalue of about 100 μm to about 120 μm, for example.

However, the width P1 of the first upper grooves GU1 and the width P2 ofthe first lower grooves GB1 are not necessarily limited to the abovenumerical value examples.

In an embodiment, the width P1 of the first upper grooves GU1 may besubstantially the same as the width P2 of the first lower grooves GB1.However, the invention is not limited thereto.

In the disclosure, when the height, width, and the like are“substantially the same,” it may include not only a case in whichnumerical values of the height, width, and the like are completely thesame but also a case in which there is a difference within an errorrange that may occur during a process despite the same design.

FIG. 5D is a cross-sectional view of taken along line II-II′ illustratedin FIG. 5A. The cutting line II-II′ of FIG. 5A may be parallel to thefirst direction DR1.

Referring to FIG. 5A and FIG. 5D together, the window PG of theinvention may include a second folding portion FP2 folded about thesecond folding axis FX2 and a third peripheral portion NFP3 and a fourthperipheral portion NFP4 which are adjacent to the second folding portionFP2. The third peripheral portion NFP3 and the fourth peripheral portionNFP4 may be spaced apart from each other in the first direction DR1 withthe second folding portion FP2 interposed therebetween.

The second portion PT2, the fifth portion PTS, and the eighth portionPT8 may correspond to the second folding portion FP2. The first portionPT1, the fourth portion PT4, and the seventh portion PT7 may correspondto the third peripheral portion NFP3. The third portion PT3, the sixthportion PT6, and the ninth portion PT9 may correspond to the fourthperipheral portion NFP4.

Referring to FIG. 5A, FIG. 5C, and FIG. 5D together, a portion foldedabout the first folding axis FX1 and a portion folded about the secondfolding axis FX2 may be different from each other. In an embodiment, thesecond portion PT2 in the first peripheral portion NFP1 and the eighthportion PT8 in the second peripheral portion NFP2 may correspond to thesecond folding portion FP2, for example. In addition, in the firstfolding portion FP1, the fourth portion PT4 and the sixth portion PT6may respectively correspond to the third peripheral portion NFP3 and thefourth peripheral portion NFP4.

Based on the second folding axis FX2, the second folding portion FP2 maybe defined as the second folding region FA2, and the third peripheralportion NFP3 and the fourth peripheral portion NFP4 may be respectivelydefined as the third and fourth non-folding regions NFA3 and NFA4.

In the second folding portion FP2, the second upper groove GU2 and thesecond lower groove GB2 may be defined.

In an embodiment, the second upper groove GU2 and the second lowergroove GB2 may not overlap each other in a plan view. In the firstdirection DR1, the second upper groove GU2 and the second lower grooveGB2 may have a shape of being alternately defined.

Each of the second upper grooves GU2 has a shape of being recessed inthe upper surface PG-F, and may have, specifically, a shape of beingrecessed in a direction from the upper surface PG-F to the lower surfacePG-B. A height t3 of the second upper grooves GU2 may be defined as anaverage value of maximum values of depths at which each of the secondupper grooves GU2 is recessed in the direction from the upper surfacePG-F to the lower surface PG-B.

The description of the height t1 of the first upper grooves GU1described above may be equally applied to a detailed description of theheight t3 of the second upper grooves GU2.

Each of the second lower grooves GB2 has a shape of being recessed inthe lower surface PG-B, and may have, specifically, a shape of beingrecessed in a direction from the lower surface PG-B to the upper surfacePG-F. A height t4 of the second lower grooves GB2 may be defined as anaverage value of maximum values of depths at which each of the secondlower grooves GB2 is recessed in the direction from the lower surfacePG-B to the upper surface PG-F.

The description of the height t2 of the first lower grooves GB1described above may be equally applied to a detailed description of theheight t4 of the second lower grooves GB2.

In an embodiment, the height t3 of the second upper grooves GU2 may besubstantially the same as the height t4 of the second lower grooves GB2.However, the invention is not limited thereto.

A width P3 of the second upper grooves GU2 may be defined as an averagevalue of the widths of the second upper grooves GU2 measured in thefirst direction DR1 on the upper surface PG-F. A width P4 of the secondlower grooves GB2 may be defined as an average value of the widths ofthe second lower grooves GB2 measured in the second direction DR1 on thelower surface PG-B.

The description of the width P1 of the first upper grooves GU1 describedabove may be equally applied to a detailed description of the width P3of the second upper grooves GU2. The description of the width P2 of thefirst lower grooves GB1 described above may be equally applied to adetailed description of the width P4 of the second lower grooves GB2.

In an embodiment, the width P3 of the second upper grooves GU2 may besubstantially the same as the width P4 of the second lower grooves GB2.However, the invention is not limited thereto.

A window PG of FIG. 5E is an embodiment illustrated which is differentfrom the window PG illustrated in FIG. 5D.

Referring to FIG. 5E, in an embodiment of the window PG, the height t1of the first upper grooves GU1 may be different from the height t2 ofthe first lower grooves GB1. In an embodiment, the height t1 of thefirst upper grooves GU1 may be greater than the height t2 of the firstlower grooves GB1, for example. Accordingly, the flexibility of theupper surface PG-F of the window PG may be further improved.

However, the invention is not limited thereto. Although not illustrated,the height t1 of the first upper grooves GU1 may be less than the heightt2 of the first lower grooves GB1. Accordingly, the flexibility of thelower surface PG-B of the window PG may be further improved.

The shapes of the second upper grooves GU2 and the second lower groovesGB2 may also be changed like the shapes of the first upper grooves GU1and the first lower grooves GB1. Hereinafter, the descriptions of thesecond upper grooves GU2 and the second lower grooves GB2 may be equallyapplied to descriptions of the first upper grooves GU1 and the firstlower grooves GB1 to be described later, and embodiments of the secondupper grooves GU2 and the second lower grooves GB2 will be omitted.

FIG. 6A and FIG. 6B are cross-sectional views illustrating an embodimentof a portion of a cross-section of a window according to the invention.

Referring to FIG. 6A, in an embodiment of the window PG, the width P1 ofthe first upper grooves GU1 may be different from the width P2 of thefirst lower grooves GB1. In an embodiment, the width P1 of the firstupper grooves GU1 may be less than the width P2 of the first lowergrooves GB1, for example. However, the invention is not limited thereto.

Referring to FIG. 6B, in an embodiment of the window PG, the width P1 ofthe first upper grooves GU1 may be different from the width P2 of thefirst lower grooves GB1. In an embodiment, the width P1 of the firstupper grooves GU1 may be greater than the width P2 of the first lowergrooves GB1, for example.

In FIG. 6A and FIG. 6B, the ratio of the width P1 of the first uppergrooves GU1 and the width P2 of the first lower grooves GB1 is notparticularly limited.

FIG. 6A and FIG. 6B illustrate a case in which the height t1 of thefirst upper grooves GU1 is the same as the height t2 of the first lowergrooves GB1. However, the invention is not limited thereto, and in FIG.6A and FIG. 6B, the height t1 of the first upper grooves GU1 may bechanged to be different from the height t2 of the first lower groovesGB1. The contents described above with reference to FIG. 5A to FIG. 5Emay be equally applied to descriptions of other components.

FIG. 7A to FIG. 7C are each a cross-sectional view illustrating anembodiment of a portion of a cross-section of a window according to theinvention.

Referring to FIG. 7A, the height t1 of the first upper grooves GU1 maybe the same as the height t2 of the first lower grooves GB1.Specifically, each of the height t1 of the first upper grooves GU1 andthe height t2 of the first lower grooves GB1 may be less than half thethickness t0 of the window PG. An average thickness of the first foldingportion FP1 in the window PG of FIG. 7A may be greater than an averagethickness of the first folding portion FP1 in the window PG of FIG. 5C.Accordingly, the impact resistance of the window PG of FIG. 7A may befurther improved.

In FIG. 7A, the width P1 of the first upper grooves GU1 may be the sameas the width P2 of the first lower grooves GB1. However, the inventionis not limited thereto.

Referring to FIG. 7B, the width P1 of the first upper grooves GU1 may bedifferent from the width P2 of the first lower grooves GB1. In anembodiment, the width P1 of the first upper grooves GU1 may be less thanthe width P2 of the first lower grooves GB1, for example.

Referring to FIG. 7C, the width P1 of the first upper grooves GU1 may bedifferent from the width P2 of the first lower grooves GB1. In anembodiment, the width P1 of the first upper grooves GU1 may be greaterthan the width P2 of the first lower grooves GB1, for example.

FIG. 8A and FIG. 8B are cross-sectional views illustrating an embodimentof a portion of a cross-section of a window according to the invention.

Referring to FIG. 8A, the height t1 of the first upper grooves GU1 andthe height t2 of the first lower grooves GB1 may be different from eachother, and the width P1 of the first upper grooves GU1 and the width P2of the first lower grooves GB1 may be different from each other.

In an embodiment, the height t1 of the first upper grooves GU1 may begreater than the height t2 of the first lower grooves GB1, and the widthP1 of the first upper grooves GU1 may be less than the width P2 of thefirst lower grooves GB1, for example.

The first upper grooves GU1 are less wide but higher than the firstlower grooves GB1, so that the flexibility of the upper surface PG-F maybe ensured.

The first lower grooves GB1 are less high but wider than the first uppergrooves GU1, so that the flexibility of the lower surface PG-B beensured.

Referring to FIG. 8B, the height t1 of the first upper grooves GU1 andthe height t2 of the first lower grooves GB1 may be different from eachother, and the width P1 of the first upper grooves GU1 and the width P2of the first lower grooves GB1 may be different from each other.

In an embodiment, the height t1 of the first upper grooves GU1 may beless than the height t2 of the first lower grooves GB1, and the width P1of the first upper grooves GU1 may be greater than the width P2 of thefirst lower grooves GB1, for example.

The first upper grooves GU1 are less high but wider than the first lowergrooves GB1, so that the flexibility of the upper surface PG-F may beensured.

The first lower grooves GB1 are less wide but higher than the firstupper grooves GU1, so that the flexibility of the lower surface PG-B beensured.

FIG. 9A to FIG. 9E are cross-sectional views illustrating an embodimentof a portion of a cross-section of a window according to the invention.

Unlike the window PG illustrated in FIG. 5C to FIG. 8B, in FIG. 9A toFIG. 9E, the first upper grooves GU1 and the first lower grooves GB1 mayoverlap in a plan view. In the third direction DR3, the first uppergroove GU1 and the first lower groove GB1 may face each other.

A portion in the window PG overlapping the first upper grooves GU1 andthe first lower grooves GB1 may have improved flexibility compared to aportion in the window PG not overlapping the first upper grooves GU1 andthe first lower grooves GB1.

Referring to FIG. 9A, the height t1 of the first upper grooves GU1 maybe the same as the height t2 of the first lower grooves GB1. In anembodiment, each of the height t1 of the first upper grooves GU1 and theheight t2 of the first lower grooves GB1 may be less than half thethickness t0 of the window PG, for example.

The width P1 of the first upper grooves GU1 may be the same as the widthP2 of the first lower grooves GB1.

Referring to FIG. 9B, the height t1 of the first upper grooves GU1 maybe different from the height t2 of the first lower grooves GB1. In anembodiment, the height t1 of the first upper grooves GU1 may be lessthan the height t2 of the first lower grooves GB1, for example.

The width P1 of the first upper grooves GU1 may be the same as the widthP2 of the first lower grooves GB1.

Referring to FIG. 9C, the height t1 of the first upper grooves GU1 maybe different from the height t2 of the first lower grooves GB1. In anembodiment, the height t1 of the first upper grooves GU1 may be greaterthan the height t2 of the first lower grooves GB1, for example.

The width P1 of the first upper grooves GU1 may be the same as the widthP2 of the first lower grooves GB1.

Referring to FIG. 9D, the height t1 of the first upper grooves GU1 maybe different from the height t2 of the first lower grooves GB1, and thewidth P1 of the first upper grooves GU1 may be different from the widthP2 of the first lower grooves GB1. In an embodiment, the height t1 ofthe first upper grooves GU1 may be greater than the height t2 of thefirst lower grooves GB1, and the width P1 of the first upper grooves GU1may be greater than the width P2 of the first lower grooves GB1, forexample. However, the invention is not limited thereto, and as describedabove with reference to FIG. 8B, the height t1 of the first uppergrooves GU1 may be less than the height t2 of the first lower groovesGB1, and the width P1 of the first upper grooves GU1 may be greater thanthe width P2 of the first lower grooves GB1.

Referring to FIG. 9E, the height t1 of the first upper grooves GU1 maybe different from the height t2 of the first lower grooves GB1, and thewidth P1 of the first upper grooves GU1 may be different from the widthP2 of the first lower grooves GB1. In an embodiment, the height t1 ofthe first upper grooves GU1 may be less than the height t2 of the firstlower grooves GB1, and the width P1 of the first upper grooves GU1 maybe less than the width P2 of the first lower grooves GB1, for example.

However, the invention is not limited thereto, and as described abovewith reference to FIG. 8A, the height t1 of the first upper grooves GU1may be greater than the height t2 of the first lower grooves GB1, andthe width P1 of the first upper grooves GU1 may be less than the widthP2 of the first lower grooves GB1.

However, the invention is not limited thereto.

FIG. 10 is a cross-sectional view illustrating an embodiment of aportion of a cross-section of a window according to the invention.

Referring to FIG. 10 , each of the height t1 of the first upper groovesGU1 and the height t2 of the first lower grooves GB1 may not beconstant. In an embodiment, FIG. 10 illustrates a case in which each ofthe first upper grooves GU1 and the first lower grooves GB1 is providedin an odd number.

In an embodiment, the height t1 of the first upper grooves GU1 maydecrease from a central portion of the first folding region FA1 towardthe first peripheral portion NFP1 and the second peripheral portionNFP2, for example. In an embodiment, the height t2 of the first lowergrooves GB1 may increase from the central portion of the first foldingregion FA1 toward the first peripheral portion NFP1 and the secondperipheral portion NFP2, for example.

However, the invention is not limited thereto, and each of the height t1of the first upper grooves GU1 and the height t2 of the first lowergrooves GB1 may decrease from the central portion of the first foldingregion FA1 toward the first peripheral portion NFP1 and the secondperipheral portion NFP2. In an alternative embodiment, each of theheight t1 of the first upper grooves GU1 and the height t2 of the firstlower grooves GB1 may increase from the central portion of the firstfolding region FA1 toward the first peripheral portion NFP1 and thesecond peripheral portion NFP2.

In an embodiment, FIG. 10 illustrates that the width P1 of the firstupper grooves GU1 are the same as the width P2 of the first lowergrooves GB1, but the invention is not limited thereto, and the width P1of the first upper grooves GU1 may be different from the width P2 of thefirst lower grooves GB1.

FIG. 11 is a cross-sectional view illustrating an embodiment of aportion of a cross-section of a window according to the invention.

Referring to FIG. 11 , the first upper grooves GU1 may have a shaperecessed in the upper surface PG-F, and the first lower grooves GB1 mayhave a shape recessed in the lower surface PG-B and penetrated to theupper surface PG-F. That is, the height t1 of the first upper groovesGU1 may be less than the thickness t0 of the window PG, and the heightt2 of the first lower grooves GB1 may be the same as the thickness t0 ofthe window PG.

In an embodiment, the width P2 of the first lower grooves GB1 maydecrease as the distance in the third direction DR3 increases. However,the invention is not limited thereto, and the width P2 of the firstlower grooves GB1 may increase, or have a constant value as the distancein the third direction DR3 increases.

In an embodiment, FIG. 11 illustrates that the width P1 of the firstupper grooves GU1 are the same as the width P2 of the first lowergrooves GB1, but the invention is not limited thereto, and the width P1of the first upper grooves GU1 may be different from the width P2 of thefirst lower grooves GB1.

However, the invention is not limited thereto, and in an embodiment ofthe window PG, at least one of the first upper grooves GU1 and the firstlower grooves GB1 may have a shape of penetrating from the upper surfacePG-F to the lower surface PG-B.

FIG. 12 is a flowchart of an embodiment of a method for manufacturing awindow according to the invention.

Referring to FIG. 12 , the method for manufacturing a window may includeproviding a mother substrate (S10) and defining a groove (S20).

A mother substrate provided in the providing of a mother substrate (S10)is a substrate for manufacturing a window, and may correspond to asubstrate before grooves are defined. The mother substrate provided inthe providing of a mother substrate (S10) may be, depending on amanufacturing operation, a glass substrate before being reinforced, butis not limited thereto, and may be a tempered glass substrate which hasundergone a reinforcement operation. In order to define a groove, themother substrate may have virtual lines defined as an extensiondirection of the groove.

Thereafter, the defining of a groove on the mother substrate (S20) maybe performed. The defining of a groove (S20) may include irradiating anintense light (e.g., laser) (S21) and etching (S22).

Laser irradiated in the irradiating of laser (S21) may overlap anirradiation point to change the refractive index of a portion of themother substrate.

The material phase of a portion of the mother substrate irradiated withthe laser may be deformed by the laser, and the refractive index ofpoints irradiated with the laser and the refractive index of points ofthe mother substrate not irradiated with the laser may be different.

The etching (S22) may include a wet-etching operation in which anetching solution is provided to the point irradiated with the laser. Amethod for providing the etching solution may be a spray method forspraying an etching solution onto a point of a mother substrateirradiated with laser, a dipping method for dipping a mother substrateinto an etching solution, or the like, but is not limited to anyparticular embodiment. The etching solution provided in an embodiment ofthe invention may include an alkali solution.

Hereinafter, with reference to each drawing, each operation of themethod for manufacturing a window in an embodiment of the invention willbe described in detail. FIG. 13A to FIG. 13C are views illustrating anembodiment of one operation of the method for manufacturing a windowaccording to the invention.

Referring to FIG. 13A, a mother substrate P-SB may include an uppersurface FS and a lower surface BS, and may have a thickness parallel tothe third direction DR3. On a first folding region FA1 of the mothersubstrate P-SB, virtual lines GL11, GL12, GL21, and GL22 for defininggrooves may be defined. In an operation to be described later, the linesGL11, GL12, GL21, and GL22 may correspond to positions at which thegrooves are defined, and may be defined parallel to an extensiondirection of the grooves.

For convenience of description, FIG. 13A illustrates lines GL11, GL12,GL21, and GL22 defined to form two grooves. The lines GL11, GL12, GL21,and GL22 may be defined parallel to the third direction DR3, which isthe extension direction of grooves to be defined. Hereinafter, the linesGL11, GL12, GL21, and GL22 are defined as first lines GL11 and GL12 andsecond lines GL21 and GL22.

Laser LL may be irradiated from the upper surface FS of the mothersubstrate P-SB toward a thickness direction of the mother substrateP-SB. In an alternative embodiment, the laser LL may be irradiated fromthe lower surface BS of the mother substrate P-SB toward a thicknessdirection of the mother substrate P-SB. The laser LL may be irradiatedonto the mother substrate P-SB parallel to the third direction DR3. Thelaser LL may be irradiated overlapping the lines GL11, GL12, GL21, andGL22. In an embodiment, the laser LL may be irradiated from the uppersurface FS of the mother substrate P-SB to overlap the first lines GL11and GL12, for example. The laser LL may be irradiated from the lowersurface BS of the mother substrate P-SB to overlap the second lines GL21and GL22.

Each of the first lines GL11 and GL12 and the second lines GL21 and GL22may be provided in a plurality of columns. However, the invention is notlimited thereto, and the first lines GL11 and GL12 may be provided inone column, and the second lines GL21 and GL22 may be provided in aplurality of columns to adjust the width of a groove to be defined at aposition at which the first lines GL11 and GL12 are defined to besmaller than the width of a groove to be defined at a position at whichthe second lines GL21 and GL22 are defined.

Points of the mother substrate P-SB irradiated with the laser LL may bemelted locally by the laser LL to cause the deformation of a phase, andaccordingly, the refractive index may be changed. Refractive indexes ofthe points of the mother substrate P-SB irradiated with the laser LL maybe different from the refractive index of the mother substrate P-SBbefore irradiated with the laser LL. The laser LL may have a degree ofintensity which may change the refractive index of one portion of themother substrate P-SB without cutting the one portion of the mothersubstrate P-SB.

The laser LL may have pulse energy. The pulse duration of the laser LLmay range from hundreds of picoseconds to tens of femtoseconds. In anembodiment, the pulse duration of the laser LL may be about 200picoseconds, for example. The pulse duration of the laser LL may varydepending on the material or thickness of the mother substrate P-SB. Thewavelength of the laser LL may be about 250 nanometers (nm) to about1500 nm or less, and may be, specifically, about 340 nm to about 1060 nmor less.

The laser LL may be a non-diffractive beam. In an embodiment, the laserLL may be a Bessel beam, for example. However, the invention is notlimited thereto, and the laser LL may be a Gaussian beam.

FIG. 13B illustrates a cross-sectional view of the mother substrate P-SBafter the irradiation of the laser LL (refer to FIG. 13A). The firstlines GL11 and GL12 may be irradiated with the laser LL (refer to FIG.13A) to form first portions P11 and P12. The second lines GL21 and GL22may be irradiated with the laser LL (refer to FIG. 13A) to form secondportions P21 and P22. For convenience of description, the first portionsP11 and P12 and the second portions P21 and P22 irradiated with laserare illustrated as hatched regions, but substantially, it may bedifficult to distinguish the first portions P11 and P12 and the secondportions P21 and P22 with the naked eye from portions not irradiatedwith the laser in the mother substrate P-SB.

Refractive indexes of the first portions P11 and P12 and the secondportions P21 and P22 after the irradiation of the laser may be differentfrom the refractive index of the mother substrate P-SB before theirradiation of the laser.

Each of the first portions P11 and P12 and the second portions P21 andP22 may have a predetermined diameter in a plan view. In an embodiment,the diameter of each of the first portions P11 and P12 and the secondportions P21 and P22 may be about 3 μm or less, for example. The laserLL changes the refractive index of the mother substrate P-SB withoutforming a physical hole therein, and sizes of portions whose refractiveindexes are changed are small, so that the appearance change of themother substrate P-SB caused by the laser may not be easily visuallyrecognized, and may be visually recognized using a high-magnificationmicroscope or the like.

Each of the first portions P11 and P12 and the second portions P21 andP22 may be extended along the third direction DR3. The first portionsP11 and P12 may be spaced apart from each other by a predeterminedinterval. The second portion P21 and P22 may be spaced apart from eachother by a predetermined interval. The predetermined interval may be ascale of a few micrometers (μm).

Gaps between the first portions P11 and P12 and the second portion P21and P22 may be spaced apart by a predetermined interval along the seconddirection DR2. According to the intervals between the first portions P11and P12 and the second portion P21 and P22, intervals between thegrooves GU1 and GB1 (refer to FIG. 13C) to be defined may vary.

Each of the first portions P11 and P12 and the second portions P21 andP22 may have a predetermined thickness along a thickness direction. Thethickness of each of the first portions P11 and P12 and the secondportions P21 and P22 may be smaller than the thickness of the mothersubstrate P-SB. By adjusting the intensity of laser, the thicknesses ofthe first portions P11 and P12 and the second portions P21 and P22 maybe controlled. According to the thicknesses of the first portions P11and P12 and the second portions P21 and P22, the depth of ach of thegrooves GU1 and GB1 (refer to FIG. 13C) to be defined may vary.

As described above, since the first lines GL11 and GL12 and the secondlines GL21 and GL22 are provided in a plurality of columns, the firstportions P11 and P12 and the second portions P21 and P22 may also beformed or provided in a plurality of columns.

An etching solution ES may be provided on the first and second portionsP11, P12, P21, and P22. The etching solution ES may be provided by aspraying method or dipping method, but is not limited to any particularembodiment. The etching solution ES may etch one portion of the mothersubstrate P-SB around the first and second portions P11, P12, P21, andP22.

The etching solution ES may include an alkali solution. In anembodiment, the etching solution ES may include a sodium hydroxide(NaOH) solution or a potassium hydroxide (“KOH”) solution, andpreferably, the etching solution ES may include the sodium hydroxidesolution, for example.

Shapes of the grooves GU1 and GB1 (refer to FIG. 13C) may vary dependingon an etching rate or etching amount. As the concentration andtemperature of the etching solution ES increase, the etching rate mayincrease. As a period of time of exposure to the etching solution ESincreases, that is, as the etching time increases, the etching amountmay increase.

Particularly, as the temperature of the etching solution ES increases,the reactivity of the etching solution ES may increase, and thus, mayincrease the etching rate. The temperature of the etching solution ESmay be room temperature or higher. In an embodiment, the temperature ofthe etching solution ES may be about 100 degrees Celsius to 150 degreesCelsius or lower, for example. When the temperature of the etchingsolution ES is lower than 100 degrees Celsius, the reactivity of theetching solution ES may decrease, and the process time for defining agroove may increase. When the temperature of the etching solution ES ishigher than 150 degrees Celsius, the mother substrate P-SB is exposed tohigh temperatures, and thus, may be damaged.

FIG. 13C illustrates a cross-sectional view of a substrate SB in whichgrooves GU1 and GB1 are defined after a predetermined period of timeafter the exposure to the etching solution ES in the state of the oneoperation illustrated in FIG. 13B.

The plurality of grooves GU1 and GB1 may be defined such that a portionof the substrate SB may be recessed through the laser irradiationoperation S21 and the etching operation S22 described above. Here, thesubstrate SB may correspond to the mother substrate P-SB in which theplurality of grooves GU1 and GB1 is defined. The description describedabove may be equally applied to descriptions of the plurality of groovesGU1 and GB1. In an embodiment, a first groove GU1 defined by beingrecessed in an upper surface FS of the substrate SB may correspond tothe above-described first upper groove GU1 (refer to FIG. 5C), forexample. In addition, a method for forming the first groove GU1 may beequally applied to a method for forming the second upper groove GU2(refer to FIG. 5D). A second groove GB1 defined by being recessed in alower surface BS of the substrate SB may correspond to theabove-described first lower groove GB1 (refer to FIG. 5C). In addition,a method for forming the second groove GB1 may be equally applied to amethod for forming the second lower groove GB2 (refer to FIG. 5D).

In an embodiment, the width P1 of the first upper groove GU1 may be thesame as the width P2 of the first lower groove GB1. However, theinvention is not limited to what is illustrated in FIG. 13A to FIG. 13C,and in an embodiment of the method for manufacturing a window, in orderto manufacture the windows of various embodiments illustrated in FIG. 5Eto FIG. 11B, positions of lines, the number of columns of laserirradiated onto the position at which each groove is defined, the timeduring which the laser is irradiated, intervals between positions atwhich the laser is irradiated, the intensity of the laser, or the likemay be adjusted. The window PG in an embodiment includes the first uppergroove GU1 extended in the first direction DR1, the first lower grooveGB1 extended in the first direction DR1, the second upper groove GU2extended in the second direction DR2, and the second lower groove GB2extended in the second direction DR2, and thus, may be folded about twoor more folding axes. Specifically, the window PG includes the firstupper groove GU1 extended in the first direction DR1 and the first lowergroove GB1 extended in the first direction DR1, and thus, may be foldedabout the first folding axis FX1 extended in the first direction DR1,and includes the second upper groove GU2 extended in the seconddirection DR2 and the second lower groove GB2 extended in the seconddirection DR2, and thus, may be folded about the second folding axis FX2extended in the second direction DR2.

The window PG in an embodiment of the invention includes the fifthportion PT5 in which the first upper groove GU1 and the second uppergroove GU2 intersect each other, and the first lower groove GB1 and thesecond lower groove GB2 intersect each other, and thus, may be foldedwith respect to each of the first folding axis FX1 and the secondfolding axis FX2 crossing each other.

In an embodiment, the grooves GU and GB recessed in each of the uppersurface PG-F and the lower surface PG-B are defined in the window PGaccording to the invention, and thus, the window PG may be preventedfrom being damaged when folded.

The display device DD including the window PG of the invention may haveimproved folding properties and improved impact resistance.

A window of the invention may be folded about each of two folding axescrossing each other.

A display device of the invention has improved folding properties, andprevent a window from being damaged when the display device is folded.

Although the invention has been described with reference to a preferredembodiment of the invention, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the invention as setforth in the following claims. Accordingly, the technical scope of theinvention is not intended to be limited to the contents set forth in thedetailed description of the specification, but is intended to be definedby the appended claims.

What is claimed is:
 1. A window comprising: a first folding portionfoldable about a first folding axis extended in a first direction, andincluding an upper surface and a lower surface facing each other; and asecond folding portion foldable about a second folding axis extended ina second direction crossing the first direction, and including the uppersurface, the lower surface and a portion of the first folding portion,wherein: a plurality of first upper grooves each of which is extended inthe first direction and recessed from the upper surface and a pluralityof first lower grooves each of which is extended in the first directionand recessed from the lower surface are defined in the first foldingportion, a plurality of second upper grooves each of which is extendedin the second direction and recessed from the upper surface and aplurality of second lower grooves each of which is extended in thesecond direction and recessed from the lower surface are defined in thesecond folding portion, the portion of the first folding portionincluded in the second folding portion is defined as a crossing portion,and the plurality of first upper grooves, the plurality of first lowergrooves, the plurality of second upper grooves, and the plurality ofsecond lower grooves are disposed in the crossing portion.
 2. The windowof claim 1, further comprising a first peripheral portion and a secondperipheral portion spaced apart from each other in the second directionwith the first folding portion interposed therebetween, wherein theplurality of second upper grooves and the plurality of second lowergrooves are defined in a portion of each of the first peripheral portionand the second peripheral portion.
 3. The window of claim 2, whereineach of the first peripheral portion, the first folding portion, and thesecond peripheral portion is foldable about the second folding axis. 4.The window of claim 1, further comprising a third peripheral portion anda fourth peripheral portion spaced apart from each other in the firstdirection with the second folding portion interposed therebetween,wherein the plurality of first upper grooves and the plurality of firstlower grooves are defined in a portion of each of the third peripheralportion and the fourth peripheral portion.
 5. The window of claim 4,wherein each of the third peripheral portion, the second foldingportion, and the fourth peripheral portion is foldable about the firstfolding axis.
 6. The window of claim 1, wherein the plurality of firstupper grooves and the plurality of first lower grooves do not overlapeach other in a plan view.
 7. The window of claim 6, wherein theplurality of first upper grooves and the plurality of first lowergrooves are alternately defined with each other.
 8. The window of claim1, wherein the plurality of first upper grooves and the plurality offirst lower grooves overlap each other in a plan view.
 9. The window ofclaim 1, wherein an average value of heights at which the plurality offirst upper grooves is recessed from the upper surface is substantiallyidentical to an average value of heights at which the plurality of firstlower grooves is recessed from the lower surface.
 10. The window ofclaim 1, wherein an average value of heights at which the plurality offirst upper grooves is recessed from the upper surface is different froman average value of heights at which the plurality of first lowergrooves is recessed from the lower surface.
 11. The window of claim 1,wherein an average value of widths of the plurality of first uppergrooves measured in the second direction from the upper surface issubstantially identical to an average value of widths of the pluralityof first lower grooves measured in the second direction from the lowersurface.
 12. The window of claim 1, wherein an average value of widthsof the plurality of first upper grooves measured in the second directionfrom the upper surface is different from an average value of widths ofthe plurality of first lower grooves measured in the second directionfrom the lower surface.
 13. The window of claim 1, wherein the crossingportion is defined in a center portion of each of the first foldingportion and the second folding portion.
 14. The window of claim 1,wherein: the plurality of first upper grooves each and the plurality offirst lower grooves each are spaced apart from each other in the seconddirection, and the plurality of second upper grooves each and theplurality of second lower grooves each are spaced apart from each otherin the first direction.
 15. The window of claim 1, wherein the pluralityof first upper grooves and the plurality of first lower grooves are eachsymmetrical about the first folding axis.
 16. The window of claim 1,wherein the plurality of second upper grooves and the plurality ofsecond lower grooves are each symmetrical around the second foldingaxis.
 17. A window comprising: a first portion, a second portion, and athird portion sequentially defined in a first direction; a fourthportion, a fifth portion, and a sixth portion sequentially defined inthe first direction, overlapping each of the first to third portions ina second direction crossing the first direction, and disposedrespectively below the first to third portions in the second direction;and a seventh portion, an eighth portion, and a ninth portionsequentially defined in the first direction, overlapping each of thefirst to third portions in the second direction, and disposedrespectively below the fourth to sixth portions in the second directionin the second direction, wherein: upper surfaces of the first to ninthportions are disposed in a same plane, and together define a firstsurface, lower surfaces of the first to ninth portions are disposed in asame plane, and together define a second surface, a plurality of firstupper grooves recessed from the first surface and extended in the firstdirection is defined in each of the fourth to sixth portions, and aplurality of second upper grooves recessed from the first surface andextended in the second direction is defined in each of the secondportion, the fifth portion, and the eighth portion.
 18. The window ofclaim 17, wherein: a plurality of first lower grooves recessed from thesecond surface and extended in the first direction is further defined ineach of the fourth to sixth portions, and a plurality of second lowergrooves recessed from the second surface and extended in the seconddirection is further defined in each of the second portion, the fifthportion, and the eighth portion.
 19. The window of claim 17, wherein:the fourth to sixth portions are foldable about a first folding axisextended in the first direction, and the second portion, the fifthportion, and the eighth portion are foldable about a second folding axisextended in the second direction.
 20. A display device comprising: adisplay module which is foldable; and a window disposed on the displaymodule, the window including: a first folding portion foldable about afirst folding axis extended in a first direction, and including an uppersurface and a lower surface facing each other; and a second foldingportion foldable about a second folding axis extended in a seconddirection crossing the first direction, including the upper surface andthe lower surface, and including a portion of the first folding portion,wherein: a plurality of first upper grooves each of which is extended inthe first direction and recessed from the upper surface and a pluralityof first lower grooves each of which is extended in the first directionand recessed from the lower surface are defined in the first foldingportion, a plurality of second upper grooves each of which is extendedin the second direction and recessed from the upper surface and aplurality of second lower grooves each of which is extended in thesecond direction and recessed from the lower surface are defined in thesecond folding portion, and the portion of the first folding portionincluded in the second folding portion is defined as a crossing portion,wherein the plurality of first upper grooves, the plurality of firstlower grooves, the plurality of second upper grooves, and the pluralityof second lower grooves are defined in the crossing portion.